[PATCH bpf-next 7/7] tools/bpftool: add perf subcommand

Yonghong Song
2018-05-15T23:45:38Z

The new command "bpftool perf [show]" will traverse
all processes under /proc, and if any fd is associated
with a perf event, it will print out related perf event
information.

Below is an example to show the results using bcc commands.
Running the following 4 bcc commands:
kprobe: trace.py '__x64_sys_nanosleep'
kretprobe: trace.py 'r::__x64_sys_nanosleep'
tracepoint: trace.py 't:syscalls:sys_enter_nanosleep'
uprobe: trace.py 'p:/home/yhs/a.out:main'

The bpftool command line and result:

$ bpftool perf
21711: prog_id 5 kprobe func __x64_sys_write offset 0
21765: prog_id 7 kretprobe func __x64_sys_nanosleep offset 0
21767: prog_id 8 tracepoint sys_enter_nanosleep
21800: prog_id 9 uprobe filename /home/yhs/a.out offset 1159

$ bpftool -j perf
{"pid":21711,"prog_id":5,"prog_info":"kprobe","func":"__x64_sys_write","offset":0}, \
{"pid":21765,"prog_id":7,"prog_info":"kretprobe","func":"__x64_sys_nanosleep","offset":0}, \
{"pid":21767,"prog_id":8,"prog_info":"tracepoint","tracepoint":"sys_enter_nanosleep"}, \
{"pid":21800,"prog_id":9,"prog_info":"uprobe","filename":"/home/yhs/a.out","offset":1159}

$ bpftool prog
5: kprobe name probe___x64_sys tag e495a0c82f2c7a8d gpl
loaded_at 2018-05-15T04:46:37-0700 uid 0
xlated 200B not jited memlock 4096B map_ids 4
7: kprobe name probe___x64_sys tag f2fdee479a503abf gpl
loaded_at 2018-05-15T04:48:32-0700 uid 0
xlated 200B not jited memlock 4096B map_ids 7
8: tracepoint name tracepoint__sys tag 5390badef2395fcf gpl
loaded_at 2018-05-15T04:48:48-0700 uid 0
xlated 200B not jited memlock 4096B map_ids 8
9: kprobe name probe_main_1 tag 0a87bdc2e2953b6d gpl
loaded_at 2018-05-15T04:49:52-0700 uid 0
xlated 200B not jited memlock 4096B map_ids 9

$ ps ax | grep "python ./trace.py"
21711 pts/0 T 0:03 python ./trace.py __x64_sys_write
21765 pts/0 S+ 0:00 python ./trace.py r::__x64_sys_nanosleep
21767 pts/2 S+ 0:00 python ./trace.py t:syscalls:sys_enter_nanosleep
21800 pts/3 S+ 0:00 python ./trace.py p:/home/yhs/a.out:main
22374 pts/1 S+ 0:00 grep --color=auto python ./trace.py

Signed-off-by: Yonghong Song <yhs@fb.com>
---
tools/bpf/bpftool/main.c | 3 +-
tools/bpf/bpftool/main.h | 1 +
tools/bpf/bpftool/perf.c | 188 +++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 191 insertions(+), 1 deletion(-)
create mode 100644 tools/bpf/bpftool/perf.c

diff --git a/tools/bpf/bpftool/main.c b/tools/bpf/bpftool/main.c
index 1ec852d..eea7f14 100644
--- a/tools/bpf/bpftool/main.c
+++ b/tools/bpf/bpftool/main.c
@@ -87,7 +87,7 @@ static int do_help(int argc, char **argv)
" %s batch file FILE\n"
" %s version\n"
"\n"
- " OBJECT := { prog | map | cgroup }\n"
+ " OBJECT := { prog | map | cgroup | perf }\n"
" " HELP_SPEC_OPTIONS "\n"
"",
bin_name, bin_name, bin_name);
@@ -216,6 +216,7 @@ static const struct cmd cmds[] = {
{ "prog", do_prog },
{ "map", do_map },
{ "cgroup", do_cgroup },
+ { "perf", do_perf },
{ "version", do_version },
{ 0 }
};
diff --git a/tools/bpf/bpftool/main.h b/tools/bpf/bpftool/main.h
index 6173cd9..63fdb31 100644
--- a/tools/bpf/bpftool/main.h
+++ b/tools/bpf/bpftool/main.h
@@ -119,6 +119,7 @@ int do_prog(int argc, char **arg);
int do_map(int argc, char **arg);
int do_event_pipe(int argc, char **argv);
int do_cgroup(int argc, char **arg);
+int do_perf(int argc, char **arg);

int prog_parse_fd(int *argc, char ***argv);
int map_parse_fd_and_info(int *argc, char ***argv, void *info, __u32 *info_len);
diff --git a/tools/bpf/bpftool/perf.c b/tools/bpf/bpftool/perf.c
new file mode 100644
index 0000000..6d676e4
--- /dev/null
+++ b/tools/bpf/bpftool/perf.c
@@ -0,0 +1,188 @@
+// SPDX-License-Identifier: GPL-2.0+
+// Copyright (C) 2018 Facebook
+// Author: Yonghong Song <yhs@fb.com>
+
+#define _GNU_SOURCE
+#include <fcntl.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <ftw.h>
+
+#include <bpf.h>
+
+#include "main.h"
+
+static void print_perf_json(int pid, __u32 prog_id, __u32 prog_info,
+ char *buf, __u64 probe_offset, __u64 probe_addr)
+{
+ jsonw_start_object(json_wtr);
+ jsonw_int_field(json_wtr, "pid", pid);
+ jsonw_uint_field(json_wtr, "prog_id", prog_id);
+ switch (prog_info) {
+ case BPF_PERF_INFO_TP_NAME:
+ jsonw_string_field(json_wtr, "prog_info", "tracepoint");
+ jsonw_string_field(json_wtr, "tracepoint", buf);
+ break;
+ case BPF_PERF_INFO_KPROBE:
+ jsonw_string_field(json_wtr, "prog_info", "kprobe");
+ if (buf[0] != '\0') {
+ jsonw_string_field(json_wtr, "func", buf);
+ jsonw_lluint_field(json_wtr, "offset", probe_offset);
+ } else {
+ jsonw_lluint_field(json_wtr, "addr", probe_addr);
+ }
+ break;
+ case BPF_PERF_INFO_KRETPROBE:
+ jsonw_string_field(json_wtr, "prog_info", "kretprobe");
+ if (buf[0] != '\0') {
+ jsonw_string_field(json_wtr, "func", buf);
+ jsonw_lluint_field(json_wtr, "offset", probe_offset);
+ } else {
+ jsonw_lluint_field(json_wtr, "addr", probe_addr);
+ }
+ break;
+ case BPF_PERF_INFO_UPROBE:
+ jsonw_string_field(json_wtr, "prog_info", "uprobe");
+ jsonw_string_field(json_wtr, "filename", buf);
+ jsonw_lluint_field(json_wtr, "offset", probe_offset);
+ break;
+ case BPF_PERF_INFO_URETPROBE:
+ jsonw_string_field(json_wtr, "prog_info", "uretprobe");
+ jsonw_string_field(json_wtr, "filename", buf);
+ jsonw_lluint_field(json_wtr, "offset", probe_offset);
+ break;
+ }
+ jsonw_end_object(json_wtr);
+}
+
+static void print_perf_plain(int pid, __u32 prog_id, __u32 prog_info,
+ char *buf, __u64 probe_offset, __u64 probe_addr)
+{
+ printf("%d: prog_id %u ", pid, prog_id);
+ switch (prog_info) {
+ case BPF_PERF_INFO_TP_NAME:
+ printf("tracepoint %s\n", buf);
+ break;
+ case BPF_PERF_INFO_KPROBE:
+ if (buf[0] != '\0')
+ printf("kprobe func %s offset %llu\n", buf,
+ probe_offset);
+ else
+ printf("kprobe addr %llu\n", probe_addr);
+ break;
+ case BPF_PERF_INFO_KRETPROBE:
+ if (buf[0] != '\0')
+ printf("kretprobe func %s offset %llu\n", buf,
+ probe_offset);
+ else
+ printf("kretprobe addr %llu\n", probe_addr);
+ break;
+ case BPF_PERF_INFO_UPROBE:
+ printf("uprobe filename %s offset %llu\n", buf, probe_offset);
+ break;
+ case BPF_PERF_INFO_URETPROBE:
+ printf("uretprobe filename %s offset %llu\n", buf,
+ probe_offset);
+ break;
+ }
+}
+
+static int show_proc(const char *fpath, const struct stat *sb,
+ int tflag, struct FTW *ftwbuf)
+{
+ __u64 probe_offset, probe_addr;
+ __u32 prog_id, prog_info;
+ int err, pid = 0, fd = 0;
+ const char *pch;
+ char buf[4096];
+
+ /* prefix always /proc */
+ pch = fpath + 5;
+ if (*pch == '\0')
+ return 0;
+
+ /* pid should be all numbers */
+ pch++;
+ while (*pch >= '0' && *pch <= '9') {
+ pid = pid * 10 + *pch - '0';
+ pch++;
+ }
+ if (*pch == '\0')
+ return 0;
+ if (*pch != '/')
+ return FTW_SKIP_SUBTREE;
+
+ /* check /proc/<pid>/fd directory */
+ pch++;
+ if (*pch == '\0' || *pch != 'f')
+ return FTW_SKIP_SUBTREE;
+ pch++;
+ if (*pch == '\0' || *pch != 'd')
+ return FTW_SKIP_SUBTREE;
+ pch++;
+ if (*pch == '\0')
+ return 0;
+ if (*pch != '/')
+ return FTW_SKIP_SUBTREE;
+
+ /* check /proc/<pid>/fd/<fd_num> */
+ pch++;
+ while (*pch >= '0' && *pch <= '9') {
+ fd = fd * 10 + *pch - '0';
+ pch++;
+ }
+ if (*pch != '\0')
+ return FTW_SKIP_SUBTREE;
+
+ /* query (pid, fd) for potential perf events */
+ err = bpf_trace_event_query(pid, fd, buf, sizeof(buf),
+ &prog_id, &prog_info, &probe_offset, &probe_addr);
+ if (err < 0)
+ return 0;
+
+ if (json_output)
+ print_perf_json(pid, prog_id, prog_info, buf, probe_offset,
+ probe_addr);
+ else
+ print_perf_plain(pid, prog_id, prog_info, buf, probe_offset,
+ probe_addr);
+
+ return 0;
+}
+
+static int do_show(int argc, char **argv)
+{
+ int nopenfd = 16;
+ int flags = FTW_ACTIONRETVAL | FTW_PHYS;
+
+ if (nftw("/proc", show_proc, nopenfd, flags) == -1) {
+ perror("nftw");
+ return -1;
+ }
+
+ return 0;
+}
+
+static int do_help(int argc, char **argv)
+{
+ fprintf(stderr,
+ "Usage: %s %s { show | help }\n"
+ "",
+ bin_name, argv[-2]);
+
+ return 0;
+}
+
+static const struct cmd cmds[] = {
+ { "show", do_show },
+ { "help", do_help },
+ { 0 }
+};
+
+int do_perf(int argc, char **argv)
+{
+ return cmd_select(cmds, argc, argv, do_help);
+}
--
2.9.5